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The Production Technology of Power Transmission Poles Impregnated in Autoclave:

The best raw material for the production of power transmission poles is pine (pinus sylvestris), which grows particularly in the North higher than 60°. It is perfectly suited for the geometric and strength parameters, and at the same time well-impregnated, which helps to protect it from rotting and other destructive factors. All arriving poles at our factory undergo incoming inspection in accordance with BS 1990-1:1984 and GOST 9463-88 standard. In our production cycle, only high quality raw material is used.

Selected logs (future poles) surface is treated mechanically on the milling debarkers «Morbark C-40», that allows to remove not only the bark but also the bast, which is necessary for providing a predetermined depth in the impregnation process. Barked poles arrive at the warehouse, where it is stacked into cells and left to dry naturally, or it is loaded on a platform and served in one of the two convective dryers with a volume of 100 cubic meters of single load each until reaching the impregnation humidity 25-28%.

Pressure treatment is by far the best method for treating wood which is to be used under conditions of severe decay potential. It can only be done at large commercial pressure-treatment plants. Wood to be treated must first be kiln-dried or well-seasoned to remove water. Various methods of pressure treatment are used, depending on the preservatives, the kind and dimensions of the wood, and the intended use of the end product.

Using this method of impregnation allows us to achieve a depth of impregnation of at least 85% of the sapwood.

Impregnation Using Water-Soluble Antiseptic CCA (Chromated, Copper, Arsenate):

In the impregnating workshop in a special 15-cubic capacity the antiseptic solution CCA is prepared, where the solution enters a120-cubic maneuvering capacitance. Barked, dried poles on trolleys are loaded into the autoclave, where the impregnation is carried out in accordance with the GOST 20022.6-93 using the method  «Vacuum-Pressure-Vacuum» at a pressure of 4-5 atmosphere and a temperature of 20-30 ° C.

In winter conditions, if necessary, a preheating procedure by steam is performed  followed by vacuumizing one. (Usually poles are fed to the autoclave for impregnating directly after drying).

After completing the cycle of impregnating, a finishing heat treatment of wood steaming and vacuuming is carried out for fixing antiseptic. As a result of the components antiseptic are finally incorporated into the structure of the wood and acquires an insoluble and safe for humans and the environment form.

Finished poles arrives at the warehouse and then shipped to the consumers in any convenient way of transport for them.

Impregnation Using Coal-Oil (Tar-Oil, Creosote):

Creosote was the first wood preservative to gain industrial importance more than 150 years ago and it is still widely today for protection of industrial timber components where long service life is essential.

Creosote is supplied as a ready-to-use solution. No dilution is necessary or mixing with other components is required before use and it is usually supplied to timber at elevated temperature by vacuum-pressure impregnation in specialized industrial treatment plants.

The chemical composition of creosote is typically a thick, oily liquid which is amber to black in color. It is a complex mixture of hundreds or even thousands of different aromatic hydrocarbons anthracene, naphthalene and phenanthrene derivatives, and at least 75% of the coal tar creosote mixture is polycyclic aromatic hydrocarbons.

Creosote is normally produced by distillation of coal-tar and refers to the portion of the coal-tar which boils between 200 degrees Celsius and 400 degrees Celsius. Most of the components in coal-tar creosote oil are heavier than water (specific density of 1,04 to 1,5 kg per liter. While normal oil floats on water, coal-tar creosote sinks. However, it tends to leave an oil slick on the water surface.

Creosote (Coal-tar) is a distillation product collected during preparation of coke from bituminous coal. It is the oldest and most widely used wood preservative. Some of the advantages of creosote are:  high toxicity to fungi and insects; low cost;  long lasting in both fresh and salt water;  noncorrosive to metals and wood;  easy to determine depth of penetration.

At RusDrevProm we use the process of “vacuum-pressure-vacuum” at a pressure of 8-12 atmosphere with a temperature of 100°C. When impregnating poles of a humidity more than 30%, a combined mode is performed “drying and impregnating”. In this case, a vacuum-drying is used with heating the poles in creosote.

Finished poles arrive at the warehouse where it withstand a few days, after which they are ready for shipment.

Standards:

Our Siberian pine (P?nus sylv?stris, Pin?ceae) which grows starting from a latitude of 59° degrees meet the highest specifications, such as:

• British Standard Specification BS 1990-1:1984; “Wood poles for overhead power and telecommunication lines. Specification for softwood poles.”
• Norme Francaise NF C67-100-1982; “Supports for overhead lines wood poles – specifications.”
• American National Standard ANSI O5.1-2008; “Wood Poles – Specifications & Dimensions.”
• European EN 351, as well as many others;